Levels are used throughout the construction industry and other industries to determine level and plumb surfaces. The most common type of level is referred to as a spirit level. The spirit level normally includes a frame which houses a closed end tube filled with alcohol, ether, or a mixture thereof. A small bubble of air is entrained in the tube and, by basic physical laws, seeks out the highest point in the tube. The tube is marked with parallel lines at equidistant points from the tube center. By observing the relationship between the parallel lines and the bubble of air, a user can visually determine whether the surface the level is resting on is substantially level. The spirit level, while useful for determining whether a surface is level, i.e., at 180 degrees, is not helpful where other angles are desired.
More sophisticated levels are known. For example, U.S. Pat. No. 5,167,075 provides a level to measure the angular displacement during pipe-bending. However, this level is cumbersome and requires the use of at least three spirit levels. In addition, this level requires some undesirable estimation of angles and undesirable rotation of parts of the level for use.
Therefore, a need in the art exists for an easy-to-use, accurate, precise and reliable level and protractor.